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排序方式: 共有1352条查询结果,搜索用时 46 毫秒
991.
V. Karimäki R. Kinnunen M. Korkea-aho J. Maalampi J. Tuominiemi G. W. van Apeldoorn D. Harting D. J. Holthuizen B. J. Pijlgroms P. Johnson P. Mason H. Muirhead G. D. Patel 《Zeitschrift fur Physik C Particles and Fields》1981,10(3):189-195
Inclusive production of∑ ±(1385) resonances is studied in \(\bar pp\) interactions at 12 GeV/c. The cross sections for∑ +(1385)+cc and∑ ? are determined to be 251±38 μb and 123±30 μb, respectively. The inclusive spectra are presented as a function of Feynman x, c.m. rapidity and the squared transverse momentump T 2 . Significant differences with the correspondingpp data are found in the longitudinal momentum distributions. The qualitative features of the production can be explained by simple quark ideas. 相似文献
992.
Shahanaz Khatun M. Ashraduzzman N. Absar F. Pervin M. Abbas Ali Luthfunnesa Bari M. R. Karim Parvez Hassan 《中国化学会会志》2007,54(2):357-364
Three lectins designated as SLL‐1, SLL‐2 and SLL‐3 were purified from small sized Sajna (Moringa oleifera L.) leaves by gel filtration of 100% ammonium sulfate saturated crude protein extract on Sephadex G‐75 followed by ion‐exchange chromatography on DEAE and affinity chromatography on Sepharose‐4B. The molecular weight of the lectins SLL‐1, SLL‐2 and SLL‐3 were 1,55,000, 1,15,000 and 85,000, respectively, as determined by gel filtration on Sephadex G‐150 and 1,60,000; 1,20,000 and 85,500, respectively, by SDS‐polyacrylamide slab gel electrophoresis. SLL‐1 and SLL‐2 are dimer in nature held together by disulfide bond (s), while SLL‐3 is a monomer. The lectins agglutinated specifically rat red blood cells and the agglutination was inhibited specifically by methyl‐α‐D‐galactopyranoside, methyl‐β‐D‐galactopyranoside and D‐galactose. The lectins SLL‐1, SLL‐2 and SLL‐3 contain 3.9, 3.4 and 2.8% neutral sugar, respectively, and the sugar compositions were glucose for SLL‐1, mannose for SLL‐2 and SLL‐3 contained either N‐acetyl‐D‐glucosamine or N‐acetyl‐D‐galactosamine or both. The lectins exhibited cytotoxicity in brine shrimp lethality bioassay. 相似文献
993.
Malik M. Ishfaq H. M. A. Karim M. A. Khan 《Journal of Radioanalytical and Nuclear Chemistry》1993,170(2):321-331
Adsorption of cesium from aqueous solutions on potassium copper nickel hexacyanoferrate(II) (KCNF) has been investigated in batch experiments and optimized as a function of concentration of acids, salts and adsorbate using a radiotracer technique. The results are presented in terms of distribution coefficient, Kd (ml·g–1). The uptake of cesium obeys a Freundlich adsorption isotherm over the concentration range of 3.7 to 37 mmol·l–1 with b values of 0.77, 0.68 and 0.56 at temperatures of 293, 313, 333 K, respectively. The Langmuir adsorption isotherm is followed in the concentration range of 15 to 75 mmol·l–1 in the same temperature range. The values of limiting adsorption concentration (Cm) have been found to be 2.58, 2.44 and 2.32 mmol·g–1. The heat of adsorption was calculated as 26.43 kJ·mol–1. The influence of a number of anions and cations on cesium retention has also been studied. Column experiments have been performed and breakthrough have been obtained under different operating conditions. The low cesium capacity of 1.1 mmol·g–1 has been obtained under dynamic conditions as compared to batch experiments. Desorption of cesium from the column has been achieved (45.4%) by nitric acid solution of 8M concentration at a flow rate of 0.5 ml·min–1. 相似文献
994.
Elena Piletska Sergey Piletsky Kal Karim Ewald Terpetschnig Anthony Turner 《Analytica chimica acta》2004,504(1):179-183
The composition of new molecularly imprinted polymers (MIPs) specific for biotin was optimised using molecular modelling software. Three functional monomers: methacrylic acid (MAA), 2-(trifluoromethyl)acrylic acid (TFAA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPSA), which demonstrated the highest binding scores with biotin, were tested on their ability to generate specific binding sites. The imprinted polymers were photografted to the surface of polystyrene microspheres in water. The affinity of the synthetic “receptor” sites was evaluated in binding experiments using horseradish peroxidase-labelled biotin. Good correlation was found between the modelling results and the performance of the materials in the template re-binding study. The dissociation constants for all MIPs were 1.4-16.8 nM, which is sufficient for most analytical applications where biotin is used as a label. 相似文献
995.
A. Mushtaq M. S. Mansoor H. M. A. Karim M. A. Khan 《Journal of Radioanalytical and Nuclear Chemistry》1991,147(2):257-261
The adsorption behaviour of99Mo in the form of molybdate and of99mTc in the form of pertechnetate on hydrated titanium dioxide was investigated at different molarities of hydrochloric acid. The adsorption capacity of molybdate on hydrated TiO2 is higher than on Al2O3. A99mTc-generator is suggested. This generator is based on the adsorption of (99Mo) molybdate on hydrated TiO2, at acidities of 0.05–0.1M. HCl.99mTc is eluted with 0.9% NaCl. Radionuclidic, radiochemical and chemical purities of the eluates were checked. This generator seems to have a great potential as compared to the traditional alumina generators. 相似文献
996.
The solubilities of potassium fluoride, chloride, and bromide in acetonitrile, N,N-dimethylformamide, and dimethylsulfoxide and in binary mixtures of these solvents were determined at 25°C. The standard molar Gibbs free energies of solution, solnG°, in the neat solvents were related to the polarizabilities and basicities of the anions and the dipole moments and acidities of the solvents. The values of solnG° in the mixtures were fitted by expressions from the quasi-lattice quasi-chemical theory. The mean number of each kind of solvent in the nearest environment of the ions was obtained from these results. 相似文献
997.
研究了稀土元素Sm、Eu、Gd对于Nb掺杂的TiO2基压敏电阻电学性能的影响. 几种稀土元素的掺杂量均为体系总量的2%(原子比), 其它原料的掺入量固定不变. 实验样品在1380 ℃烧结, 保温4 h. 实验发现, Sm、Eu、Gd等稀土元素可以有效降低TiO2基压敏电阻的压敏电压, 但对于非线性系数的影响不很明显. 对于Sm、Eu、Gd掺杂, 实验得到的压敏电压值分别为12.7、14.7和16.1 V. 通过对试样的阻抗分析发现, Sm、Eu、Gd掺杂对于压敏电阻的介电性能有显著影响, 单独掺杂Sm或Gd的试样具有很低的介电常数和介电损耗, 并且具有很高的电阻率. 相似文献
998.
不同主链"甲壳型"高分子的合成及其液晶性研究 总被引:1,自引:0,他引:1
"甲壳型"液晶高分子(MJLCP)的概念是周其凤等[1]在1987年首次提出的,随后分别被文献[2~8]所证实.由于液晶基元对空间的要求,液晶高分子主链采取尽可能伸展的构象.虽然它们在化学结构上属于侧链型,但在分子形态上更接近于主链型液晶高分子,但至今尚不清楚其产生液晶性的原因. 相似文献
999.
1000.
γ-MnOOH multipods were synthesized by a low temperature hydrothermal method. The synthetic procedure is based on the use of PEG200 to reduce KMnO4 upon controlling the volume of PEG200. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) were used to characterize the products. All pods of them are single crystals, the diameter of each pod is about 40~120 nm and the length is about 800~2 400 nm. A possible formation mechanism was proposed that the intermediate products with a lamellar morphology curled into γ-MnOOH nanorods during the reaction process at first, and then γ-MnOOH multipods formed for the multi-nuclei growth on the tips of the γ-MnOOH nanorods when they were good crystallization. 相似文献